RAM 4x1GB - or 2x2GB - What's the issue? Or is it MoBo?

[naviscan]

:shocked;

Mushkin "HP2-6400-DDR2"[996533R] With MoBo: Asus "P5N-E SLI", What gives...?

PROBLEM : UNABLE to use all Four RAM slots/4GB set for RAM default: 800MHz!
SOLUTION : It boots & works flawlessly by slacking RAM down to 667MHz, Only!
COMMENT : Regardless of using either OS, WinXP - or Vista Ultimate 64-Bit!
Question 1 : What's wrong with using RAM at lower than default frequency?
Question 2 : How come that x64 OS and system does not help after booting?

My rig's config skinny (any bragging is irrelevant):

* MoBo: Asus P5N-E SLI; (No SLI activated)
* CPU: E6600 (B2) - with Lots of cooling!
* RAM: Mushkin PC6400 (800MHz) = 4 x 1GB Identical modules [996533R]
* GFx : ATI Radeon X1950 Pro (512MB GDDR3 in Blue PCIe x16 slot
* Boot in: 2 x Raptors (36GB) in SATA RAID 0 (striping) = OS + Progs
* Storage: 2 x Seagate (250GB) in SATA RAID 0 (striping) = Backups, Cloning "C:\"
* OS now : Windows Vista Ultimate x64

In BIOS 0401 to 0608 - setting RAM to [Auto] or [Manual] at default 800MHz would render system unstable (with or w/out OS x32/x64 installed), and plenty of errors in running Memtest!

Slowing down RAM to 667MHz with all known manual tweaks, voltage up to 2.2V, Clocks to 2T, the whole shebang: System is stable, loads w/out a glitch, no BSOD, no reboots, and Memtest torture test overnight gives no errors! AND ALL ARE IN DUAL CHANNEL!

So why spending money on 4 x 1GB 800MHZ RAM - to lower their freq to 667MHz - and not just buy cheaper RAM at 667MHz default speed?

Or keep the RAM and dump the MoBo?

Last - without any Sandra/other performance Tests - what is the disadvantage of running your rig at lower than default speed?

Any idea is highly appreciated...

 

[myocardia]

Welcome to anandtech. Nearly all motherboards require raising the northbridge voltage by either .1 or .2v, when using 4 sticks of RAM. Overclocking the cpu only exacerbates the problem, in most instances.

 

[n7]

Yeah, sadly, 4 dimms = trouble on the majority of motherboards.

The P35/X38 chipsets would be the best for running 4 dimms right now, but they even can have some issues.

I actually just sold my 4x1 GB of Corsair, since i was tired of being unable to run even one MHz over 399 (1596 FSB) when 3+ dimms were installed.
2x2 GB Mushkin is en route to hopefully cure that issue.

 

[lopri]

It's the board. I have no doubt that the Intel chipsets can handle 4 DIMMs. It's just that the mobo manufacturers don't pay much attention on making/testing their boards with 4 sticks configuration. That's why I was impressed when I learned that my 680i can handle 4 sticks of 2GB DIMM. I also was able to run 4GB (4x1GB) of DDR2 800/CL3 on Bad Axe 2 (wasn't easy). It's relatively easy to run 4 sticks on AMD platform, but that's no surprise knowing that the CPU has a high quality IMC built-in.

My suggestion is that one should really forget about memory overclocking when using 4 sticks on Intel platform. There is little to be gained from that but the cost will be huge. Besides, the advantage of higher capacity vastly over-weighs high frequency/tight timings these days, and under exact same configuration (ratio/frequency/timing) I saw slight increase of performance with 4 sticks over 2 sticks due to interleaving.

 

[TC91]

if you cant run the memory at the higher clocks with 4 sticks, then you could try running the ram @ tighter timings and maybe the 1T command rate. I find for my kingston ram that unlinking it to CL3 667 and 1T command rate gives me more bandwidth and performance (according to everest) than CL4 800 2T by quite a bit.